Heart rate is an important cardiovascular variable that is frequently used to measure the intensity of an exercise/workout. The most common way to express heart rate is in beats per minute.
Heart rate is just one of the ways that the intensity of an exercise can be measured. This article will not delve into all the methods of measuring exercise intensity as that is a topic for another time, instead, we will focus solely on heart rate.
How to Calculate Your Maximum Heart Rate
Maximal heart rate (HR) is the rate at which your heart beats under maximal physiological demand. While there can be individual variation that can be attributed due to training, stature, body composition, lung volume and other cardiovascular variables, the biggest factor contributing to max heart rate that is used in the literature is age.
Measuring heart rate is most prominently used in aerobic exercise like running, biking, and swimming. Using heart rate to measure other forms of exercise would not be recommended as there are more suitable ways to interpret the intensity of the workout.
The two most popular equations to calculate heart rate max include:
The traditional method to calculate heart rate, called the Fox and Haskell’s method, is simply 220 minus your current age. For example, if you are 25 years old your maximal heart rate would be 220 – 25 = 195 beats per minute. This traditional method should be taken with a grain of salt as all the participants in this study were men under the age of sixty who did not exercise regularly. This is should be used in a general sense as there are a multitude of extraneous variables that may offset this equation, training being a large one. This is the equation adopted by the CDC and the American Heart Association because it is easy to calculate and works for the general population.
A more modern method is called the Stevens Creek’s method. Using this method max heart rate is calculated by (205 – [age/2]). For example, if you are 25 years old your max heart rate is (205 – [25/2]) = 192.5 beats per minute.
As you can see both calculations have a fairly similar value and both have been shown to be accurate. Fox and Haskell’s equation tends to overestimate a young person’s max HR and underestimate an older person’s max HR which is why Stevens Creek’s is increasing in use.
Why Your Maximal Heart Rate is Useful
As stated previously heart rate is a useful indicator of exercise intensity, so if you understand what your physiological max is you can gauge the intensity of any exercise based on how close you are to this max.
In the older method recommended by the CDC:
Moderate-intensity exercise is defined as being between 64% – 76% of your max HR so if you are 25 years old and your HR max is 195 your target range for moderate physical activity would be 125-148 beats per minute.
Vigorous-intensity exercise is defined as being between 77% – 93% of your max HR so again if you are 25 years old your HR max is 195 your target range for intense physical activity would be 150-181 beats per minute.
The Karvonen method is a more modern approach to finding heart rate zones which includes resting heart rate. This is superior because resting heart rate is often a good indicator of the efficiency of the cardiovascular system. The formula follows as (Max HR- Resting HR) x Training %+ Resting HR= Target HR For example if you are 25 and your target zone is moderate-intensity exercise at 70% of your HR max (195 – 70) x 0.70 + 70 = 157.5 beats per minute
In the traditional method, a 70% exercise intensity would give an HR of 136.5 bpm.
Exercise intensity should be inversely proportional to exercise volume/duration, meaning the higher the intensity the shorter the duration and the lower the intensity the longer the duration. As an example a run at 85% of max HR for 15 minutes vs a run at 65% of HR for 45 minutes.
Heart rate can differ depending on the form of exercise an individual is doing, swimming is known to have lower heart rates than running.
Common Target Heart Rate Calculation Could Be Off By 30 BPM > The Kelsey Report. (2019, October 20). https://www.dougkelsey.com/right_heart_rate/.
Gulati, M., Shaw, L. J., Thisted, R. A., Black, H. R., Bairey Merz, C. N., & Arnsdorf, M. F. (2010). Heart rate response to exercise stress testing in asymptomatic women: the st. James women take heart project. Circulation, 122(2), 130–137. https://doi.org/10.1161/CIRCULATIONAHA.110.939249
Sporis, G., PhD., Vucetic, V., PhD., Jukic, I., PhD., Omrcen, D., Msc, Bok, D., MagEd, & Custonja, Z., MagEd. (2011). How Reliable Are the Equations for Predicting Maximal Heart Rate Values in Military Personnel? Military Medicine, 176(3), 347-51. http://cyber.usask.ca/login?url=https://www.proquest.com/scholarly-journals/how-reliable-are-equations-predicting-maximal/docview/856118236/se-2?accountid=14739